1. Technical Field
The present invention relates to an organic semiconductor device, a method for producing an organic semiconductor device, an organic electroluminescent device, and a method for producing an organic electroluminescent device.
2. Related Art
In general, organic electroluminescent devices (hereinafter, referred to as “organic EL devices”) for use in displays each include a substrate; an organic layer having a light-emitting sublayer that emits light and a hole transport sublayer that transports holes; a cathode; and an anode, the organic layer being held between the cathode and the anode, and the organic layer, the cathode, and the anode being disposed on the substrate. The light-emitting sublayer and the hole transport sublayer of the organic EL device are laminated. An electron from the cathode is combined with a hole from the anode in the light-emitting sublayer to emit light.
Examples of a method for forming the two organic sublayers, i.e., the light-emitting sublayer and the hole transport sublayer, include a method (dry process) in which materials to be formed into the light-emitting sublayer and the hole transport sublayer are sequentially deposited by evaporation on the substrate to laminate the two sublayers; and a method (wet process) in which materials to be formed into the light-emitting sublayer and the hole transport sublayer are dissolved or dispersed in an organic solvent to form liquid compositions, and after the resulting liquid compositions are applied on the substrate to form films, the organic solvent is evaporated. Examples of the wet process include ink-jet processes. Organic layers can be easily formed on large area substrates by ink-jet processes. Thus, ink-jet processes are particularly promising processes for producing, for example, organic EL devices for use in displays that have larger sizes in recent years. JP-A-2000-77185, JP-A-2000-208254, and JP-A-2000-243300 are examples of related art.
However, in the case where organic layers are formed by ink-jet processes, lyophobic or lyophilic properties of surfaces to which liquid compositions are applied are often nonuniform, thus resulting in nonuniformity in thicknesses of the formed films, in many cases. Other organic semiconductor devices such as devices including laminated organic films, e.g., organic transistors, also have the problems as well as organic EL devices.